This is rated a 15 - Quite scary at times, unsuitable for little children.
The Troll Umbreon
Jackson was playing around with his Pokemon Silver game, training his Eevee with lots of care in Goldenrod. He hoped to evolve it into an Espeon and he checked it's happiness. It was almost at the top. Jackson walked South to the Route below, and a battle commenced. A wild Drowzee appeared out of the blue. Jackson sent out his prized Eevee, and pressed the attack button. Nothing appeared but Guillotine. Jackson jumped, as this wasn't usual, and went into the "Pokemon" section. Eevee's name changed to "KILLER". Jackson freaked out and dropped his Gameboy. Then, came a Text Box from Eevee. It said "Eevee wants to know if you truly like him. Do you?". Then Jackson clicked "No" and the screen went black. A few seconds after, a bloody Eevee appeared. The game stated Eevee was evolving, and it stated Eevee evolved into Umbreon.
The Umbreon had a crooked smile, bloody tail, bloody ears and bloody feet. Jackson went up to his game one more time. He turned the game off, and looked up "Umbreon with a Crooked Smile, Bloody Tail, Bloody Ears and Bloody Feet". Nothing had appeared. For some reason it came up to a distorted, deserted page of Serebii. The Unown Theme played on the Gameboy, and the screen flashed on again, the bloody Umbreon once again on the Screen. Then, Jackson played the song "Eye of the Tiger" to get the creep out of his system, but that only made matters worse. The bloody Umbreon appeared out of the Gameboy, half the height of Jackson. The Gameboy had turned off again, listing the words "GAME OVER". The Umbreon made a growl and turned the Computer off. "Oh hey, oh hey, OH HEY?!!!" The Umbreon somehow said, and Jackson was standing horrified on the heater, his heart beating fast in his chest. "There is no escape..." Came a silent mutter from something else. Jackson jumped on the ground and ran into the hallway, the darkest place of his house. "Oh my god, I've been kind to it, NOW IT'S HUNTING ME!" Jackson screamed. "Come back, come back, COME BACK!!!" The Umbreon said, blood pouring down it's cheek and getting a claw out. It scraped it on the Oven, which hurt Jackson's ears.
He carefully traveled to the Living Room to turn the lights on. However, the lights did not come out, and a laugh boomed around the room. He tried turning on the Computer, which overreacted and made an electric shock, and the TV, in which The bloody Umbreon came up on, with some blood pouring down it's face. Nothing lit up. Jackson used the phone, and managed to call 3 of his very close friends. They all came, and a bloody Umbreon with a Saw stood up in front of them. The four people hid just about anywhere in the house, and The bloody Umbreon went up to Jackson, with the Saw on turbo. In fact, the door was locked, so there was no other place Jackson can go now. The Umbreon edged closer gradually to Jackson, as Paul, one of his friends, checked the GameBoy. "Uh uh, uh uh!" The Umbreon sung, stabbing Jackson with the Saw. Jackson fell to the floor, with an open chest. The GameBoy started reading "R.I.P Jackson".
Paul heard Jackson's scream and darted down the stairs only to see Jackson lying on the floor, and The bloody Umbreon having more blood. Paul quickly hid in the Basement, telling Tom about the Events. The Umbreon slowly and silently walked down the stairs. "Oh hey, oh hey, OH HEY?!!!" The Umbreon said again, walking towards Tom. He dropped the Saw and sharpened his claws, and then, both boys started running. Paul was always the fastest out of the two, and Tom was about 1 feet slow, and the bloody Umbreon caught Tom. "PAUL!" Tom screeched, as he was killed by the bloody Umbreon's claws. Paul had no other choice but to run, as the bloody Umbreon was waiting. Brad stepped down the stairs and read the GameBoy, where Jackson's dead body was lying. It had another Text Box from Umbreon.
"Umbreon: Nobody will be leaving me..." It said, and the Unown Song got more static. Brad tried turning the game off, but another Text Box from Umbreon appeared. "Umbreon: You think you can escape me just like that?! I'm coming for you next." It said. The Unown Music got to a great frequency, and Brad felt ill. Paul arrived with Brad, who had stopped moving completely, and poked him with a stick. He fell to the ground, his eyes starting to bleed, his nose completely blocked, and his ears squirting blood. The Umbreon appeared right behind Paul, and Paul poked it with a stick. Paul quickly erased the data of the Pokemon Game, and the Umbreon was slowly disappearing into the GameBoy. Its sprite came up on the Gameboy with a grunt, and as Data was deleted, a picture of it being beaten came up on the Gameboy. Paul turned the GameBoy off, and it didn't stop him. The Umbreon was out of the place for good, but it costed a few lives, and the entire carpet was stained with blood. Paul left the messed up house, and never came back.
"Hehahahahaa!" Jackson laughed. "Nobody apart from Paul has ever survived it! So never perform The Curse Of The Bloody Umbreon, UNLESS YOU WANT TO JOIN ME." Jackson spat with a smirk.
I'm afraid I can't answer that, as currently it is too hard to read!
You really would want to use some spacing and paragraphing there. Start a new paragraph whenever the general subject changes or when someone else talks, and use a line of spacing between each paragraph (much like this post or other stories on the forums; different from how books do it, but basically things computer screens aren't the best for reading things in the first place, so this is the usual method for formatting stories posted online).
At a quick glance, watch for small mistakes too; e.g.:
The Umbreon had a crooked smile, bloody tail, bloody ears and bloody feat.
feet, I presume.
It's sprite came up on the Gameboy with a grunt
Its; "It's" is short for 'it is', while Its is the possessive one that you want here (not 'It is sprite came up').
Try some more description as well and show us what the character felt rather than telling us; rather than saying 'he stood horrified' mention some details that'd show the reader that. Did his hands shake, heartbeat thump loudly, and so forth?
But main thing first; use paragraphs so it doesn't potentially give readers sore eyes before they look for a story that is better presented, I suggest.